Electronic component positioner for loader vehicles and the like

ABSTRACT

A conventional hydraulic fluid pump is hydraulically coupled bia a self-centering control valve means to a hydraulic cylinder having a reciprocatable cylinder rod coupled to a vehicle component. An electromagnet is disposed to latch the control valve means in a selected position when energized. Switch means is secured to the hydraulic cylinder, and means for actuating the switch means is secured to the cylinder rod for translation therewith. A logic circuit is connected to the switch means and to the electromagnet, whereby the electromagnet is energized in response to the degree of movement, and a first direction of movement, of the cylinder rod to latch the control valve means. The electromagnet is deenergized via the switch means and the means for actuating, when the cylinder rod reaches a preselected position proceeding from the opposite direction. This unlatches the control valve means which allows it to seek its self-centered position. Thus, fluid flow to the hydraulic cylinder ceases when the vehicle component reaches a preselected position.

United States Patent Fuzzell i 1 ELECTRONIC COMPONENT POSITIONER FOR LOADER VEHICLES AND THE LIKE Primary ExaminerL. T. Hix Attorney, Agent, or Firm-Phillips, Moore, Weissenherger, Lempio & Strabala [75] lnventor: Joe E. Fuzzell, Peoria, Ill. [73] Assignee: Caterpillar Tractor Company, [57] ABSTRACT Peoria. Ill. A conventional hydraulic fluid pump is hydraulically coupled bia a self-centering control valve means to a [22] Filed l973 hydraulic cylinder having a reciprocatable cylinder 1211 Appl. No.: 412,208 rod coupled to a vehicle component. An electromagnet is disposed to latch the control valve means in a r Relmed Appllcauon Dam selected position when energized. Switch means is se- [62] DlVlSlOn of Ser. No. 287.604, Septv ll, 1972, Pat. Cured t0 the hydraulic cynnden and means for actuap ing the switch means is secured to the cylinder rod for translation therewith. A logic circuit is connected to Cl 317/1485 R; 307/252 R; 307/254 the switch means and to the electromagnet, whereby [511 lm. Cl. I-IOlh 47/32 the electromagnet is energized in response to th {581 new of Search 317,135 [485 gree of movement, and a first direction of movement, 307/252 254 of the cylinder rod to latch the control valve means. The clectromagnet is deenergized via the switch {56] References means and the means for actuating, when the cylinder T D STATES PATENTS rod reaches a preselected position proceeding from 2.331.108 10/1943 Ganahl 91/358 A the opposite direction. This unlatches the control 3.151.311 9/1964 Spector et a1 317/135 A valve means which allows it to seek its self-centered 3.420393 1/1969 Omon 91/358A position. Thus. fluid flow to the hydraulic cylinder 3534-562 8/1970 Fume" i 4 214/762 ceases when the vehicle component reaches a prese- 3,667,723 (1/1972 Schneider 91/358 A lected position 3 Claims, 3 Drawing Figures .?L I 8E 90 m 88 l r 8 N- 92 7 l 1 66 1 1 53 62 i 1 e i 17,. l 68 76 1E 5/ 74 1 1 112 1 i 84 OFF 1 1 ON 1 l mji' l 1 l l 12-1 1 ELECTRONIC COMPONENT POSITIONER FOR LOADER VEHICLES AND THE LIKE This is a division, of Ser. No. 287,604, filed Sept. ll, I972, now U.S. Pat. No. 3,782,248.

BACKGROUND OF THE INVENTION l. Field The invention relates to an electronically operated positioning system for selectively and automatically positioning buckets, blades, or other vehicle components on heavy equipment vehicles and the like.

2. Prior Art Various types of control systems have been contemplated for providing automatic positioning of various vehicle components; for example, a bucket on a bucket loader, etc. Typically, such positioning systems are hydraulically, mechanically or electrically controlled.

Hydraulic positioning systems suffer from control problems when malfunctions occur in the hydraulic system. For example, a leak in the slave cylinder or in the hydraulic circuits can cause bucket drifting ranging from slight movement to drifting simulating a slow dump. A broken supply line almost completely incapacitates the positioning control system. External rc' pairs are time-consuming, particularly if the line to the tank has to be replaced. If an internal repair or adjustment has to be made in the hydraulic system, it is generally necessary to drain the hydraulic tank, which causes excessive down-time.

Electrical positioning systems overcome most of the inherent problems of the above-mentioned hydraulic systems, in that they are more reliable, more readily serviced, and are external and thus independent of the main hydraulic apparatus. However, most electrical positioning systems utilize micro-switch means meehani cally coupled to cams, recessed rods, etc., attached to the positioning hydraulic cylinder to indicate the position of the bucket. See for instance, U.S. Pat. No. 3,420,393. Thus, the combination is subject to wear, dirt, vibration, etc., common to earthmoving apparatus, with the associated maintenance and breakdown problems.

In addition, prior art electrical positioning systems fail to provide desired functioning flexibility in that no provisions are made to allow the operator to readily perform various operations, e.g., as when fish tailing, etc., the bucket. Typical prior art electrical positioning systems provide the disadvantage of latching the opera tor controls in the rack-back" position whenever the control lever is moved to the latter position, as when fish tailing. The operator must then manually override the latched condition. Accordingly, the operator must avoid moving the control lever to the rack-back position if he does not wish the lever to be held in such position, which complicates the operators handling of the vehicle, for example, as when performing the fish tailing action.

SUMMARY OF THE INVENTION The invention provides an improved solid state electronic control circuit for controlling the tilt, position, attitude, etc, of a selected component on a loader, grader, vehicle and the like To this end, a control lever is coupled to a self-centering control valve, which selectively directs hydraulic fluid to a tilt cylinder having a reciprocatable rod coupled to the vehicle component. An electromagnet is disposed to hold or latch the lever in the rack-back position when energized. The electromagnet is coupled to a solid state switch assembly,

which contains a pair of adjacent, normally open switches, and a logic circuit adapted to distinguish the 5 component operating mode and to selectively provide energizing current to the electromagnet. The pair of switches are adapted to close when placed in a magnetic field, which is selectively provided by a permanent magnet secured to the end of a rod which is, in turn, secured to the reciprocatable cylinder rod. The magnet passes adjacent the switches as the cylinder rod reciprocates.

During the rod extension, the magnet successively passes adjacent the pair of switches in one direction, which causes the solid state logic circuit to energize the electromagnet. When the control lever is then placed in the rack-back position, it is held in such position by the electromagnet. Deenergization of the electromagnct occurs via the logic circuit when the hydraulic rod is retracted, whereby the permanent magnet passes adjacent the switches in the opposite direction. The con trol valve and the control lever returns to a neutral position, whereupon further movement of the hydraulic rod, and thus of the component, ceases. Selected placement of the permanent magnet with respect to the degree of extension of the hydraulic rod determines the preselected position, tilt, orientation, etc., of the vehicle component being controlled.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a simplified elevation of a track-type loader vehicle with loader bucket, and of the basic arrangement of the invention component positioner.

FIG. 2 is a simplified electrohydraulic schematic of one embodiment of the invention combination.

FIG. 3 is a schematic diagram of the logic control circuit depicted in block schematic in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. I, a track-type loader has a bucket I2 pivotably supported as at 14 by one end of a pair of laterally spaced lift arms, only one of which is shown at 16. The lift arms 16 are pivotally secured at their opposite ends to a pair of laterally spaced towers integrally secured to the loader frame, one of which is indicated at 18. A hydraulic tilt cylinder 20, having an extcndable cylinder rod 22, is pivotally intercoupled between each tower l8 and the bucket I2 via tilt linkage, which includes a lever 24 pivotally mounted to lift arm I6 and a link 26 connecting the lever 24 to the bucket 12.

Regarding more particularly the invention positioner apparatus, and referring to FIGS. 1 and 2, a manually operable, control lever 28 is located adjacent an operators station 30, and is operably connected to a spring actuated, self-centering control valve 32. The latter is designed to selectively direct hydraulic fluid from a pump source 34 (FIG. 2) to the tilt cylinder 20, to control the position of the bucket 12. An electromagnet 36 is suitably located, whereby the control lever 28 can be pivoted against the electromagnet and thus be held in the *R" or rack-back position when the clectromagnet is energized.

The clectromagnet 36 is connected by a lead 38 to a switch assembly 40, containing a pair of spaced-apart switches 42,44. The switch assembly 40 further includes a logic control circuit 46 (FIG. 3) which detects the bucket Operating mode and provides current to selectively energize the electromagnet at predetermined periods during the bucket position and in response to its direction of motion.

Switches 42.44 are preferably solid state switches which operate via the Hall effect, and conduct current when placed in a magnetic field. In accordance with the invention, a magnetic field is provided by a permanent magnet 48 secured to the end of a control rod 50, where the latter is demountably attached at its other end to the extendable cylinder rod 22. The control rod 50, with attached magnet 48. is disposed to pass adjacent the switches 42,44 as the rod 22 is extended and retracted.

Extension of rod 22 from the fully retracted rackback position to the dump position, causes the magnet 48 to pass over switches 42 and 44 from left to right on the schematic of FIG. 2. As will be more fully explained with respect to a detailed description of the logic circuitry of FIG. 3, this action permits current to flow to the electromagnet 36.

Upon completion of the dump operation, the operator places the control lever 28 in the R position. and since the electromagnet 36 is energized, the lever 28 will remain in this position until released by cessation of current to the electromagnet. Deenergization of the electromagnet 36 is provided by passage of magnet 48 over the switches 44,42 from right to left on the schematic, as the rod 22 retracts to rotate the bucket 12 back from the dump position. The self-centering spring of the hydraulic control valve 32 urges the control lever 28 to the H or hold position, stopping further retraction of the cylinder rod 22 and thus further movement of the bucket [2. Suitable placement of the magnet 48 with respect to the position of the hydraulic rod 22 will assure that the bucket I2 is stopped in the proper load ing position to begin the next work cycle.

The solid state switch assembly 40 is connected by a lead 52 to the positive terminal of a battery 54. A fuse 56 is inserted between the assembly and the battery for circuit overload protection. The electromagnet 36 and the negative terminal of the battery are grounded. A hydraulic system pressure switch S8 is disposed between the battery and ground. and remains closed during the operation of the vehicle. but automatically functions to break the circuit when the vehicle is shut down. Similarly, the switch 58 may be operated by engine oil pressure, or other operating parameters. Addi tional switches. such as a master disconnect switch (not shown) may also be placed in the circuit as required.

A schematic diagram of an embodiment of the logic circuit 46 contained within the solid state switch assembly 40 is shown in FIG. 3. A transistor 60 is disposed between the positive lead 52 and the lead 38 extending to electromagnet 36. Transistor 62 has a grounded emitter and its base is connected through limiting resistor 68 and normally nonconducting switch 42 to ground. The collector of transistor 62 is connected to the base of the transistor 64. The emitter of transistor 64 is connected through the silicon controlled rectifier (SCR) 66 to the base of the transistor 60. A diode 70 providing reverse polarity protection. is disposed in the positive lead 52.

A zener diode 72 is connected between the positive lead 52 and ground to provide a predetermined reference voltage to the normally nonconductive switches 42. 44. A current-limiting resistor 74 provides protection for the zener diode 72. Resistors 76 and 78 similarly serve to limit current through transistors 62, 64. A resistor 80 is placed between the base of the transistor 62 and ground to prevent current leakage through the transistor by providing a reverse bias to the base when the switch 42 is non-conductive. A diode 82 and a limiting resistor 84. placed between the switch 44 and the SCR 66, provide high voltage and current protection respectively for the switch 44 when the SCR is conducting.

To prevent transient electric pulses from triggering the SCR 66, a capacitor 86 is placed across the anode and cathode thereof, and a capacitor 88 is similarly placed across its gate and cathode.

To provide a reverse bias to the base of transistor 60 and thereby assure that the transistor remains in a nonconducting state when the SCR 66 is nonconducting, a resistor 90 is placed between the base of the transistor and the lead 38. A diode 92, placed between the lead 38 and ground serves to eliminate induced voltage from the electromagnet 36 whenever the current supplied to the electromagnet is interrupted.

By the above-described arrangement. a selected device, herein specifically shown as electromagnet 36. can be energized or de-energized via a given voltage source. battery 54, in response to conduction or nonconduction of a conductive device siliconcontrolled rectifier 66. Leads 38 and 52 and transistor 60 com prise circuit means which are operatively associated with SCR 66 to couple the electromagnet 36 to battery 54 in response to conduction through SCR 66 and to uncouple electromagnet 36 from battery 54 upon termination of conduction through SCR 66.

In operation, the above-described circuit functions in the following manner. With the bucket 12 loaded and in the rack-back position. rod 22 and consequently rod 50 attached thereto will be in retracted position. In the absence of a magnetic field in the proximity of the switches 42, 44. the switches are nonconducting, thereby preventing the application ofa positive voltage to the base of the transistor 60. The absence of such a positive voltage prevents transistor 60 from conducting current to the electromagnet 36.

The circuit is thus inactive. and the operator is thus free to move the control lever 28 to the "D or dump position to empty the bucket 12. The control valve 32 then directs pressurized fluid, as required. to the cylinder 20, and rod 22 begins an outward extension.

During extension, the permanent magnet 48, mounted on rod 50 which in turn is secured to rod 22 for integral movement therewith, first passes adjacent switch 42. When magnet 48 is directly adjacent switch 42. the switch will conduct current to the base of transistor 62 permitting the transistor to become conductive. Since the emitter is grounded. the collector and base of the transistor 64 will also be at substantially zero voltage potential. Transistor 64 will therefore be nonconduetive. As the rod 22 continues its extension. the magnet 48 will move away from the switch 42. whereby current is no longer conducted to the base of the transistor 62 and the latter transistor becomes nonconductive. As a result. a positive voltage is thus provided to the base of transistor 64. permitting the transistor to conduct current to the anode of the SCR 66.

The continued extension ofhydraulic rod 22 will next bring the magnet 48 directly opposite the switch 44 whereby current is conducted by the switch to the gate of SCR 66. This will trigger the gate, enabling the SCR to conduct current to the base of the transistor 60. The SCR will continue to conduct as long as a current flows therethrough. With a positive voltage thus provided at its base, transistor 60 conducts current to the electromagnet 36 to energize the latter.

After completion of the dump operation, when the operator is desirous of returning the bucket 12 to the proper dig position, the control lever 28 is moved to the R or rack-back position. As electromagnet 36 is now energized, the lever 28 is held in the rack-back position until the electromagnct is deencrgized or until its holding force is manually overriden by the operator.

The bucket 12 returns from the dump position as rod 22 retracts. The magnet 48 first passes adjacent the switch 44 to once again supply current to the gate of the SCR 66. Since the SCR is already conducting this action has no effect on the operation of the circuit, and the electromagnct 36 remains energized. As the rod 22 continues its retraction, the switch 44 opens again. As magnet 48 passes directly adjacent the switch 42 it becomes conductive, and a positive voltage is supplied to the base of the transistor 62. The latter transistor thus becomes conductive, thereby interrupting the positive voltage present at the base of the transistor 64, as previously described.

As a result, transistor 64 becomes nonconductive, and the SCR 66 opens to thus interrupt the current to the base of the transistor 60. Consequently, transistor 60 also becomes nonconductive and current flow to the electromagnct 36 is interrupted, causing the latter to deenergize. When this occurs, the self-centering spring of the hydraulic control valve 32 urges the control lever 28 to the H or hold position, thus stopping further retraction of the rod 22. Such action occurs at a predetermined position of the rod 22 such that the bucket 12 is in the desired position for subsequent loading or digging.

It may be seen, with a loaded bucket 12 in the rackback position, the operator may dump the load by moving control lever 28 to the dump position. As the load is being dumped, the electromagnct 36 is energized when the magnet 48 passes adjacent the magnetic field sensitive switches 42,44 from left to right on the schematic.

Having dumped the load, the operator may retract the bucket 12 from the dump position by moving the control lever 28 to the rack-back position. Because the electromagnct is now energized, the lever 28 is maintained in the latter position until the magnet 48 passes adjacent the switches 44,42 preceding from the opposite direction, i.e., from right to left on the schematic. As this occurs, the electromagnct 36 is deenergized and the bucket 12 automatically stops in the proper loading position, ready to begin the next work cycle, without direction from the operator subsequent to his placing the lever 28 in the rack-back position.

As may be seen, switches 42 and 44 comprise first and second sequentially operable triggering means each of which operates when permanent magnet 48 passes adjacent thereto. The switches are closed during operation thereof and are open upon termination of operation thereof. in a sequence of operations from a loading position to a dumping position and then back to the loading position. the first triggering means, i.e., switch 42, will terminate, the second triggering means,

i.e., switch 44, will operate and terminate, then operate and terminate again, followed by operation of the first triggering means.

When the first triggering means operates, transistors 62 and 64 respond to such operation to interrupt conduction of SCR 66, thereby rendering it nonconductive. When the first triggering means terminates, transistors 62 and 64 respond to condition SCR 66 to conduct. SCR 66 will thereafter conduct when a gate pulse is applied thereto. A gate pulse will be applied to SCR 66 in response to operation of the second triggering means, i.e., switch 44. Once SCR 66 is turned on by such a gate pulse, SCR 66 will remain conductive until the first triggering means, i.e., switch 42, again operates to turn SCR 66 off.

It is to be noted that the arrangement described above will allow the operator to fish tail the bucket 12 to facilitate the loading operation without interference from the rack-back detent apparatus, as is common on prior art electrical bucket positioners. Fish tailing is the operation wherein the bucket 12 is rocked back and forth by the repetitious movement of the control lever 28 from the rack-back to the dump position. Fish tailing is unhindered by the bucket positioner of present invention since bucket movement is normally limited between the loading position and the full rack-back position during the fish tailing operation. Since electromagnet 36 is never energized in this mode, there is no effect on the movement of the lever 28, i.e., the lever is not latched via the electromagnct.

What is claimed is:

l. A logic control circuit for energizing and dcenergizing a selected device via a given voltage source, said logic control circuit comprising:

a conductive device;

circuit means operatively associated with said conductive device and adapted to couple said selected device to said voltage source in response to conduction through said conductive device and to uncouple said selected device from said voltage source upon termination of conduction through said conduction device;

first and second sequentially operable triggering means having a sequence of operations that after termination of said first triggering means said second triggering means operates and terminates and then operates and terminates again and then said first triggering means operates;

means responsive to operation of said first triggering means for rendering said conductive device nonconductive during operation of said first triggering means and for conditioning said conductive device for conduction after termination of operation of said first triggering means;

means responsive to operation of said second triggering means for initiating conduction through said conductive device during operation of said second triggering means and for maintaining conduction through said conductive device until a subsequent operation of said first triggering means.

2. A logic control circuit as set forth in claim 1 wherein said conductive device is a silicon controlled rectifier, wherein the means responsive to operation of said first triggering means controls the path of conduc tion through said silicon controlled rectifier and wherein the means responsive to operation of said second triggering means applies a conduction-initiating 7 8 gate pulse to the gate of said silicon controlled rectifier comprise a switch which is closed during operation during operation of said second triggering means. thereof and open upon termination of operation 3. A logic control circuit as set forth in claim 2 thereof. wherein said first and second triggering means each 

1. A logic control circuit for energizing and deenergizing a selected device via a given voltage source, said logic control circuit comprising: a conductive device; circuit means operatively associated with said conductive device and adapted to couple said selected device to said voltage source in response to conduction through said conductive device and to uncouple said selected device from said voltage source upon termination of conduction through said conduction device; first and second sequentially operable triggering means having a sequence of operations that after termination of said first triggering means said second triggering means operates and terminates and then operates and terminates again and then said first triggering means operates; means responsive to operation of said first triggering means for rendering said conductive device nonconductive during operation of said first triggering means and for conditioning said conductive device for conduction after termination of operation of said first triggering means; means responsive to operation of said second triggering means for initiating conduction through said conductive device during operation of said second triggering means and for maintaining conduction through said conductive device until a subsequent operation of said first triggering means.
 2. A logic control circuit as set forth in claim 1 wherein said conductive device is a silicon controlled rectifier, wherein the means responsive to operation of said first triggering means controls the path of conduction through said silicon controlled rectifier and wherein the means responsive to operation of said second triggering means applies a conduction-initiating gate pulse to the gate of said silicon controlled rectifier during operation of said second triggering means.
 3. A logic control circuit as set forth in claim 2 wherein said first and second triggering means each comprise a switch which is closed during operation thereof and open upon termination of operation thereof. 